I know what you’re thinking. Oh no, weird scienc-y type stuff to understand, but you’d be incorrect. As I will try to demonstrate, the first law of thermodynamics underpins all that renewable energies are trying to do.
To recap, there are four laws of thermodynamics, the zeroth law, the first, the second and the third. These imaginatively titled laws of thermodynamics control how energy is controlled, and how it behaves on Earth and in the wider universe.
For the interested, these 4 laws are defined as follows (via Wikipedia):
- The zeroth law of thermodynamics allows the assignment of a unique temperature to systems which are in thermal equilibrium with each other.
- The first law of thermodynamics mandates conservation of energy and states in particular that the flow of heat is a form of energy transfer.
- The second law of thermodynamics states that the entropy of an isolated macroscopic system never decreases, or, equivalently, that perpetual motion machines are impossible.
- The third law of thermodynamics concerns the entropy of a perfect crystal at absolute zero temperature, and implies that it is impossible to cool a system to exactly absolute zero.
What the first law of thermodynamics states is that energy is never lost, it is converted into another form of energy. We see that everyday in our cars, which are never more than about 20% efficient. In fact a modern car is more efficient as a producer of heat than it is as a moving vehicle.
In terms of green engineering we must consider this in all aspects of power system designs. For instance, when solar rays are collected on a solar panel, the individual photon packets hit the panel and are converted into a Direct Current supply. This then gets converted again (depending on the design of the system) into an Alternating Current supply that can be utilised around your home.
At each stage of the process, whenever energy is converted from one form to another there will be inefficient transfer of energy. What this means is that when converting the solar energy into DC current the energy that is converted will be changed into many different forms – heat, light, noise, electricity. If you were to add up the different amounts of each type converted, then it would equal the amount of solar energy collected by the solar panel.
The same principles of energy conversion apply to all different kinds of renewable energy calculations. It may be that the types of energy are different, but the resulting energy sum will not break the fundamental rules of the First Law of Thermodynamics.
